Abstract
the varying areas or japan during 1975/76, we found the outt>rears orclinically infectious coryza in the flocks routinely vaccinated with killed vaccines, preparedwith Haemophilus gallinarum strain No. 221. Out of 63 Haemophilus isolates, the 53 werecatalase-negative Ilaemophilus strains which were compared biologically and immuno-logically with II. gallinarum strain No. 221 as a reference. All the catalase-negative isolateswere capsulated and required both V factor and chicken serum, but not X factor forgrowth, and were identified as Haemophilus paragallinarum from the results of biologictests. Different from strain No. 221, none of the isolates had hemagglutinating activity.The biologic properties were similar to strain No. 221, with the exception of 4 strains inthe sugar fermentation patterns. All the isolates were highly pathogenic to both chickenand its embryos. Serologically, we found to be a single serotype among the isolates, butdifferent from strain No. 221 by cross-agglutination tests. No cross-immunization wasobserved between the isolates and strain No. 221. Relationship between If. paragallinarumand Katos H. gallinarum strain No. 221 being used for the present vaccine was discussed.
